Finite Time Command Filter Control For Cascade Continuous Stirred Tank Reactor

Because of the simple operation,sufficient reaction and easy control of cascade continuous stirred tank reactor(CSTR),it has become one of the most important core equipment in chemical and biochemical industry.However,it brings difficulties in designing a controller because of its complex second order nonlinear dynamic,strong coupling,time variability characteristics and uncertainty.Therefore,in this thesis,the control of cascade continuous stirred tank reactor is taken as the research object,the finite time command filter controller and finite time command filter fault tolerance controller are designed by the backstepping method,command filter,finite time control technology and fuzzy logic system.The main research contents of this thesis include the following three aspects:First,a mathematical model of cascade continuous stirred tank reactor is constructed,and the controller is designed based on the backstepping method.First of all,a mathematical model is built for continuous stirred reactor based on the principle of dynamics of the reactor,and on this basis,the error equation is created.The controller of cascade continuous stirring method is designed by using backstepping method,and its stability is proved based on Lyapunov function.Then,the effectiveness of the proposed method is demonstrated through simulation.Finally,the "differential explosion" problem and the slow rate of convergence problem existing in the traditional backstepping method are analyzed,providing the basis for subsequent improvement.Second,in order to improve the tracking precision and rate of cascade continuous stirred tank reactor,a finite time command filter controller is proposed.The "differential explosion" problem existing in the traditional backstepping method are resolved effectively by adopting the command filtering control technology,introducing error compensation signals and creating the Lyapunov function.Besides,the finite-time control method is introduced to improve the tracking rate of the system.Finally,the effectiveness and feasibility of the controller designed in this thesis are verified by simulation.Third,a method of designing an adaptive fuzzy finite time controller is proposed for sensor faults with fixed deviation and failure.In view of the possible failure of detecting elements on the cascade continuous stirred tank reactor during operation,the unknown parameters in fuzzy logic approximation sensor fault and system are introduced to design the self-adaptive finite-time fault tolerance controller in combination with the finite-time control and command filtering technology.The simulation results show that the proposed algorithm can reach the stable state no matter whether the sensor is faulty or not.The adaptive command filtering fault tolerance control proposed in this thesis is superior to the finite time command filtering controller in performance and can converge to a small area around the original point.